* Gold rises to three-week high; dollar falls
* Oil prices slip to three-month low
* Sears lower after warning of 'going concern' doubts
* Nike falls after quarterly revenue misses expectations
* Dow down 0.12 pct, S&P flat, Nasdaq up 0.16 pct (Updates to open)
By Tanya Agrawal
March 22 (Reuters) - The S&P 500 and the Nasdaq were little changed on Wednesday as investors increasingly worried whether President Donald Trump will be able to push ahead with his pro-growth policies.
The Dow was lower in morning trading, dragged down by a 6.2 percent fall in Nike after the world's largest footwear maker's quarterly revenue missed estimates amid intensifying competition in North America.
Trump on Tuesday tried to rally Republican lawmakers behind a plan to dismantle Obamacare, his first major legislation since assuming office in January.
Republican leaders aim to move the controversial legislation to the House floor for debate as early as Thursday, amid concerns over support from party lawmakers.
Some investors fear that if the healthcare reform act runs into trouble or takes longer-than-expected to pass, then Trump's tax reform policies may face setbacks.
The concerns triggered the biggest one-day fall since the November election on Wall Street on Tuesday.
"The markets were reminded yesterday the 'Trump trade' is not a one-way trade and there's room for disappointment as actions on tax cuts and infrastructure spending might not materializes as quickly as we want," said Anastasia Amoroso, global market strategist at J.P. Morgan Private Bank in Houston.
"The pronounced fall in yields across the world is not helping market sentiment at the moment either."
U.S. 10-year Treasury yields fell to three-week lows on Tuesday and the gap between U.S. and German 10-year government borrowing costs hit its narrowest since November.
The S&P 500 has run up about 10 percent since the election in November, spurred mainly by Trump's agenda of tax cuts and infrastructure spending, but valuations have emerged as a concern.
The benchmark index is trading at about 18 times forward earnings estimates against the long-term average of 15, according to Thomson Reuters data.
At 9:38 a.m. ET (1338 GMT) the Dow Jones Industrial Average was down 23.89 points, or 0.12 percent, at 20,644.12, the S&P 500 was down 0.11 points, or 0.00 percent, at 2,343.91.
The Nasdaq Composite was up 9.55 points, or 0.16 percent, at 5,803.37.
Five of the 11 major S&P sectors were lower, with the financial index's 1.32 percent fall leading the decliners.
The sector, the top performer since the November election, suffered its worst daily drop since June on Tuesday. Bank of America, JPMorgan, Citigroup and Wells Fargo fell about 1 percent.
Oil prices also dipped and slipped back to three-month lows after data showed U.S. crude inventories rising faster than expected.
Gold prices rose to a three-week high and the dollar index , which measures the greenback against a basket of currencies, was at 99.78, near the six-week low of 99.64 reached on Tuesday.
Sears Holdings slumped 11 percent to $8.18 after the retailer warned on Tuesday about its ability to continue as a going concern after years of losses and declining sales.
Declining issues outnumbered advancers on the NYSE by 1,598 to 976. On the Nasdaq, 1,268 issues fell and 984 advanced.
The S&P 500 index showed seven new 52-week highs and five new lows, while the Nasdaq recorded seven new highs and 30 new lows. (Reporting by Tanya Agrawal; Editing by Sriraj Kalluvila)